Equipment control in a sterile environment using the Gyromouse and a new interface, the user interface (UI) wand

Providing the surgeon/interventionist with controlling devices that avoid the need for interference of an assistant could enable more direct control and reduce errors due to miscommunication or misinterpretation. Therefore the need for an input device controlling equipment from the sterile environment is high. We evaluated the usability of two hand-held interfaces; an acceleration-sensitive Gyromouse and the User Interface Wand (UI Wand), a new prototype pointing device. The evaluation consisted of a quantitative evaluation in a laboratory setting and a qualitative evaluation using a simulated clinical setting. A quantitative tapping task was performed on a computer screen using target objects of different sizes and positioned at different distances, resulting in a set of indices of difficulties (ID's) based on Fitts' Law. The qualitative task was performed in the simulated clinical setting where images and patient data were viewed and manipulated, and a printer and two loudspeakers controlled. In the quantitative evaluation, the Gyromouse showed to be 25+/-3% (mean+/-SD, n = 11, p<0.05) faster during the tapping task than the UI Wand for ID's>2.5 bits and equally fast for ID's <2.5 bits. In the qualitative evaluation 10 of 11 subjects preferred the UI Wand over the Gyromouse and the UI Wand was considered to enable the quickest control. Both input devices are able to control equipment from the sterile environment. With the Gyromouse, the cursor often has to be searched for after activating, because the cursor remains where it is left and shifts because of drift. Despite being slower and the need for large targets, the UI Wand is preferred due to the absolute pointing characteristic; the cursor is where you are pointing at and, therefore, it is always clear where the cursor is.